Differential Diagnosis of Fibromyalgia Syndrome

The differential diagnosis of fibromyalgia syndrome is broad and includes various conditions that can mimic its symptoms. Here's a categorized list of potential diagnoses:

• Single Most Likely Diagnosis
  • Chronic Fatigue Syndrome: This condition shares many symptoms with fibromyalgia, including widespread pain, fatigue, and sleep disturbances. The key difference lies in the primary complaint, with chronic fatigue syndrome focusing more on profound fatigue.
• Other Likely Diagnoses
  • Rheumatoid Arthritis: Early stages of rheumatoid arthritis can present with widespread pain and morning stiffness, similar to fibromyalgia. However, rheumatoid arthritis typically involves more joint swelling and systemic symptoms.
  • Lupus: Systemic lupus erythematosus can cause widespread musculoskeletal pain, fatigue, and sleep disturbances, overlapping with fibromyalgia symptoms. Lupus, however, often includes other systemic manifestations such as skin rashes and kidney involvement.
  • Hypothyroidism: Thyroid hormone deficiency can lead to muscle pain, fatigue, and sleep problems, which are also common in fibromyalgia. A simple blood test can differentiate hypothyroidism from fibromyalgia.
  • Anxiety and Depression: These psychiatric conditions can manifest with somatic symptoms similar to fibromyalgia, including pain and fatigue. A thorough psychiatric evaluation is necessary to distinguish them.
• Do Not Miss Diagnoses
  • Multiple Myeloma: Although rare, multiple myeloma can cause widespread bone pain and fatigue. Missing this diagnosis could be fatal, making it crucial to consider in the differential diagnosis, especially in older adults.
  • Lyme Disease: In its later stages, Lyme disease can cause widespread pain and fatigue, similar to fibromyalgia. Given its potential for serious complications if untreated, Lyme disease should not be overlooked, particularly in endemic areas.
  • Sleep Apnea: Sleep apnea can lead to fatigue, sleep disturbances, and even musculoskeletal pain due to poor sleep quality. While not immediately life-threatening, untreated sleep apnea can have significant health consequences.
• Rare Diagnoses
  • Ehlers-Danlos Syndrome: This genetic disorder can cause widespread musculoskeletal pain, fatigue, and sleep disturbances due to its effects on connective tissue. It's less common but should be considered in patients with a family history or other suggestive features.
  • Mitochondrial Myopathies: These are a group of disorders affecting the mitochondria, leading to muscle weakness, pain, and fatigue. They are rare and typically present with additional symptoms such as neurological deficits or gastrointestinal issues.
  • Sjögren's Syndrome: An autoimmune disorder that can cause widespread pain, fatigue, and sleep disturbances, along with its hallmark symptoms of dry eyes and mouth. It's less common than other differential diagnoses but should be considered, especially if there are suggestive symptoms.